The Effects of Impact on Design Features

Abstract

This report concerns with finding a simplified model for an injection molding machine, which consists of a hydraulic piston that forces some molten metal into a mold.

The model currently used by Husky ignores all effects except the deformation of the piston and housing, which is assumed to be elastic. The impact is modelled using a mass-spring system, where the force of impact is obtained for a given impact velocity, system mass and pre-calculated “spring” constants for the impacting bodies. In order to determine the importance of the presence of the hydraulic fluid, the compressibility of the molten metal, and the leakage past the screw tip, we will assume that the deformation of the piston and housing can be ignored. However, in order to make quantitative predictions of the impact forces, it is necessary to include the effects due to the compressibility
of the machine parts. Thus, we also investigate a model that, like the current Husky model, uses a mass-spring system to incorporate the elastic deformation of the piston and the housing.